porphyritic

The name is thought to derive from blue porphyritic crystals, which are no longer visible.

Most were breccias, but they did find one porphyritic basalt.

The rock is porphyritic granite, a very strong form of granite.

More commonly, chondrules display what is known as a porphyritic texture.

They are very commonly porphyritic, vitreous, and sometimes even vesicular.

It may have any texture from glassy to aphanitic to porphyritic.

Between the two is an area of garnet bearing porphyritic andesite.

The soil, in fact, was bestrewn with quartz and porphyritic rocks.

Often vapor loss from a magma chamber will cause a porphyritic texture.

The surrounding loose rock was cleared away by the ice sheet leaving the hard porphyritic core behind.

In thin section, dacites may have an aphanitic to porphyritic texture.

A granitic rock with a porphyritic texture is sometimes known as a porphyry.

Porphyritic textures develop when conditions during cooling of a magma change relatively quickly.

The microgranite is porphyritic with a very fine groundmass.

The most common igneous rock type is porphyritic hornblende diorite.

It also has intrusions of green stone and porphyritic rocks with feldspar crystals.

He began to realize the colossal wealth which lay guarded behind the great porphyritic granite pillars.

The hill consists predominantly of porphyritic rock.

Most types of igneous rocks may display some degree of porphyritic texture.

Porphyritic rocks are formed when a column of rising magma is cooled in two stages.

Porphyritic rocks occur between the schists and the quartzites.

Porphyritic andesite is dark grey with white crystals of plagioclase feldspar embedded.

Only one exhibits a porphyritic texture.

This porphyritic texture is indicative of multi-stage cooling of magma.

The leucite is often present in two sets of crystals, both porphyritic and as an ingredient of the ground mass.